题目内容：

A new study suggests that washing dishes by hand is healthier than using a dishwasher.

Nobody likes doing the dishes, but it turns out that doing this task might pay off in an unexpected way. According to a new study published in the Journal of Pediatrics, washing dishes by hand instead of using a dishwasher might prevent the development of allergies (过敏).

Researchers in Sweden surveyed the parents of 1,029 children aged 7 and 8. They discovered that children whose families hand-washed the dishes instead of using a machine were less likely to have allergies.

Earlier research has shown that dishes washed by machine are cleaner than those washed by hand. So why would kids who eat with slightly dirtier plates be better when it comes to preventing allergies? One explanation is based on a theory known as the “hygiene hypothesis,” which says the reason why kids develop allergies is that their environment is actually too clean. Your immune system keeps you healthy by fighting germs like viruses and bacteria. But when you have allergies, it overreacts and tries to fight ordinary things like pollen(花粉) or certain foods.

Being exposed to germs, especially early in life is good training for the immune system, says the lead author of the study, Dr. Bill Hesselmar of Queen Silvia Hospital in Sweden. “You stimulate the immune system in various ways and it becomes tolerant.”

This study shows that while using the dishwasher might be easier, the old-fashioned method of cleaning up could be better for your health.

1.What is the benefit of washing dishes by hand?

A. Hand-washed dishes are cleaner than those washed by machine.

B. Washing dishes by hand is easier than washing by machine

C. Washing dishes by hand costs less time than washing by machine

D. Washing dishes by hand might reduce the chance of developing allergies

2.What does the underlined word “it” in paragraph 4 refer to?

A. bacteria    B. germs

C. the immune system    D. allergy

3.Which of the following statements is true according to the passage?

A. Using a dishwasher can prevent us from having allergies.

B. Exposure to germs early in life may improve kids’ immune system.

C. Our immune system can only fight bacteria and viruses.

D. Children should use dirty plates when they have meals.

4.What is the main idea of the passage?

A. The clean environment accounts for kids’ developing allergies.

B. Whether parents should wash dishes by hand or use a dishwasher.

C. Washing dishes by hand may prevent kids from getting allergies.

D. What “hygiene hypothesis” is and how our immune system works.